If an engine is designed to produce 450 hp with the perfect fuel blend, perfect fuel system tuning, perfect ignition timing curve, perfect altitude, perfect atmospheric conditions, perfect operating temperature but can be tuned to run reliably, and more importantly, more functionally, and have an output of 430 hp under most fuels and operating conditions, which is the better choice?

Each and every component in a motor vehicle is a compromise. You can follow the factory's choices based on what was available at that time, or you can make a few alterations to accomodate today's technologies. But if you are driving the car with today's fuel, not tapping a 40 year old reserve, you'd best tune for it. The alcohol content may mean you need to run a richer mixture than factory spec. The added oxygenates may mean richer jetting is needed. The lower octane may mean you need a less agressive timing curve, or a later curve, or less timing overall.

Ignition, for instance. Back in the early '80s everybody ditched the stock coils in favor of Accel Super Coils. Stronger spark = more power, if you believe the ads.

At 150 psi cylinder compression it may take 25,000 volts to ignite the charge with the spark plug. Does that mean a 40,000 volt coil will do a better job? Not unless your old coil was weaker than spec. If you're running cylinder pressure of 190 psi, maybe you want that 40,000 volts. How do you know? Read, ask, try. If it doesn't work for you, try something else. And ask a lot of questions until you understand. I'm always asking.